Combined effects of ridge–furrow ratio and urea type on grain yield and water productivity of rainfed winter wheat on the Loess Plateau of China

Abstract

Ridge–furrow ratio can affect the grain yield (GY) and water productivity (WP) of rainfed winter wheat under the ridge–furrow plastic mulching (RFM) system. However, the combined effects of urea type and ridge–furrow ratio on GY and WP remain unclear. Two urea types [conventional urea (CU) and controlled-release urea (CRU)] and four planting patterns [rainfed flat planting (F) and the RFM system with three ridge–furrow ratios [20 cm:40 cm (R2F4), 40 cm:40 cm (R4F4) and 60 cm:40 cm (R6F4)] were tested during three winter wheat growing seasons from October 2018 to June 2021. The results showed that R2F4, R4F4 and R6F4 increased GY by 51.6%, 109.5% and 115.2%, and increased WP by 38.0%, 77.1% and 80.3% compared with F, respectively, with the maximum GY and WP under R4F4. Compared with CU, CRU produced higher GY and WP, with mean values of 3460.6 kg ha−1 and 15.4 kg ha−1 mm−1 under CU, and 3937.9 kg ha−1 and 16.7 kg ha−1 mm−1 under CRU, respectively. The RFM system decreased the plot-to-plot variation of GY by 18.9% compared with F, but there was no significant difference between CU and CRU. The RFM system enhanced soil water use rate and crop evapotranspiration, thereby promoting dry matter accumulation ultimately, and this trend was more obvious at higher ridge–furrow ratios. Compared with CU, CRU had higher crop evapotranspiration and dry matter, but there were no differences in soil water use rate and growing season length between the two urea types. In conclusion, a ridge–furrow ratio of 40 cm: 40 cm combined with CRU was recommended for improving GY and WP of rainfed winter wheat on the Loess Plateau of China.